Acid vat dyeing of animal fibers



Patented June 22, 1954 UNITED STATES PATENT OFFlCE ACID VAT DYEIN G OF ANIMAL FIBERS No Drawing. Application January 15, 1951, Serial No. 206,125

8 Claims. 1

This invention relates to a process for the rapid dyeing of animal textile fibre with vat dyestuffs.

Animal fibres, especially wool, and textile materials containing the same, cannot be readily dyed in the piece with vat dyes from conventional alkali hydrosulfite vats because of the injurious effect of the alkali on the fibre or because of unlevel effects caused by premature oxidation. To overcome this difficulty, it has been proposed heretofore to apply vat dyestuffs to animal fibre materials in the form of leuco compounds in acid media.

Thus, U. Patent 1,900,172 indicates that mixed fabric of wool and cellulose acetate can be dyed or printed in solid shades with vat dyes by acidifying an alkaline hydrosulfite vat of the dyestufi with acetic acid in the presence of a dispersing agent, working the material in the bath for somewhat more than one hour, and oxidizing by treatment for five minutes with an aqueous sulfuric acid-bichromate bath. Alternatively, for printed materials, the leuco compound of the vat dyestufi is maintained in dispersion in a thickened aqueous acid medium which is printed on the material and dried, the dyestufi being fixed by steaming and developed by the aforesaid treatment in an oxidizing bath containing a sulfuric acid and a bichromate.

As an improvement upon the aforesaid process, U. S. Patent 2,107,526 discloses application of a dispersed leuco compound of a vat dyestuff to textile material, drying for about 15 to 30 minutes to evaporate most of the water under nonoxidizing conditions, steaming if desired, and oxidizing by hanging in the air or treatment in an aqueous oxidizing bath.

According to U. S. Patent 2,450,767, animal fibre textile material is padded with dispersed unreduced vat dyestuff in an acid medium, the dyestufif absorbed by the fibre being reduced to leuco form in acid media, and developed by subjecting the material to oxidizing treatment.

The foregoing processes depend on the absorption of dyestuff by the fibre and involve timeconsuming operations either for the fixation or application of the dyestufi. They are therefore inconvenient or unsuitable for continuous dyeing of animal fibre textile materials in present commercial practice. I

It is an object of this invention to provide a process for dyeing animal fibre, especially textiles containing such fibre, with vat dyes under acid conditions, wherein the treatment operations can be carried out rapidly and continuously to produce shades of excellent fastness properties,

especially to Washing and light.

5 and developed on the material without intermediate drying or any other treatment, but instead, merely by passing the padded material immediately through an aqueous acid bath maintained near its boiling point (about 200 to 212 F.) for a period of about one minute. Development can be readily effected by exposure to atmospheric oxygen, and the dyeings produced show excellent fastness to light and washing.

The padding liquor employed in accordance with this invention is advantageously prepared by dissolving the vat dyestufi" in aqueous alkaline hydrosuifite solution, adding an acid-stable dispersing agent such as an alkyl-aryl sulfonic acid, a sulionated formaldehyde-naphthalene or -phenol condensation product, N -oleyl-N -methyl taurine or the like, and acidifying (preferably with acetic or formic acid) to a pH of 3 to 6.

Preferably, a booster compound is included to accelerate penetration and fixation of the dyestuff on the fabric. Such compounds are, for instance, hydroxylated aliphatic polyamines of the type disclosed in U. S. Patents 2,256,805-809, inclusive, but are preferably hydroxy-polyethenoxy tertiary amines resulting from condensation of higher aliphatic hydrocarbon primary monoamines of 10 to 18 carbon atoms with at least 4,

and preferably up to 20, molecular equivalents of ethylene oxide. The latter preferred fixation assistants have the formula:

(C aCHrOh-H RN\ (CHzOHaOMH wherein R is a higher aliphatic hydrocarbon radical of 10 to 18 carbon atoms, n and m are integers, each at least 2, their sum being the total number of ethylene oxide radicals condensed per mol of an amine having the formula RNI-Iz, especially a whole number from 4 to 20. These compounds have been found especially cffective for rapid fixation and penetration of animal fibre material by the leuco vat dyestuffs contained in the acid aqueous dispersion applied in the padding step of this invention.

Padding of the animal fiber material with the acid dispersion of a leuco vat dye can be effected in conventional padding equipment and fixation can be carried on in a booster box, or preferably a Williams unit, in which the ratio of the liquor to material is maintained at a relatively low value. Fixation and development is efiected by 3 passing the padded material directly through an aqueous acid bath (e. g. in a Williams unit) maintained. at a temperature near the boiling point, particularly 200 to 212 F. The acid bath preferably has a pH of 1 to 3 at 25 C. The duration of the immersion required is of the order of onehalf to one minutes, and is thus readily and conveniently carried out by continuously passing the material through the bath. Development can be effected by passing the material from the bath through an oxidizing solution such as aqueous sulfuric acid bichromate or aqueous persulfate or hydrogen peroxide. However, such oxidizing baths are not required, since development can be satisfactorily effected by exposing the material to air after it leaves the hot acid treatment bath.

The material is then advantageously rinsed, soaped, again rinsed and dried.

My invention is illustrated by the following examples, wherein parts and percentages are by Weight.

Ewample 1 10 parts of 2,2 bis thionaphthene indigo (Colour Index No. 1207) are vatted by treatment with 3 parts of caustic soda and 10 parts of sodium hydroxide in 300 parts of water at 130 F. 20 parts of the sodium salt of a formaldehyde-naphthalene sulfonic acid condensation product dissolved in 100 parts of Water, are added to serve as a dispersing agent, and the resulting vat is acidified by addition of a solution of 18 to 20 parts of 28% aqueous acetic acid in 100 parts of water. A stable dispersion of the vat dye leuco compound is thus obtained. A woolen fabric is continuously padded with the resulting dispersion, the retention of the bath by the fabric being 100%. Directly after padding, the material is passed through an aqueous bath composed of 2 parts of formic acid per 100 parts of water, maintained at boiling temperature (about 212 F). Duration of immersion of the goods in the bath is about 1 minute. On exposure to air, development occurs and the material is dyed in a bluish-red shade of excellent fastness to light and Washing.

Example 2 parts of 6,6dichloro-4,4-dimethyl-2,2-bisthionaphthene-indigo are vatted by treatment with 2.5 parts of sodium hydrosulfite and 2.8 parts of caustic soda in 100 parts of Water at 175 C. parts of formaldehyde-naphthalene sodium sulfonate condensation product and 30 parts of a condensation product of 8 to 10 mols of ethylene oxide with 1 mol of higher aliphatic primary monoamines derived from fatty acids of natural fats (e. g. consisting mainly of oleylamine or of laurylor stearylamine) are added to serve as a dispersing agent and fixation accelerator. 4.5 parts of formic acid in 900 parts of water at 90 F. are added to the vat to render it acidic. The resulting bath contains the leuco compound of the vat dyestuff in aqueous dispersion. Wool flannel is padded with the acidified vat by passing it through the bath, the duration of the immersion in the bath being about 5 seconds. The padded material is immediately passed through an aqueous bath composed of one of formic acid to each 100 parts of water, maintained at the boiling point (about 212 F). Duration of the immersion in the latter bath is about one minute. After issuing from the boiling acid bath, the material is exposed to air to develop the dyestuff, yielding a brilliant pink dyeing of excellent fastness to light and washing.

4 Example 3 30 parts of 2,5-di-(p-chloroanilido) -1,i-benzoquinone (Colour Index No. 1176) are vatted by treatment with 12 parts of sodium hydrosulfite and 8 parts of caustic soda in 500 parts of water at F. 15 parts of a formaldehyde-naphthalene sulfonate condensation product and 30 parts of a higher alkyl monoamine polyethylene oxide condensation product, as described in Example 2, are also included in the bath. 8 parts of o-phosphoric acid are added to acidify the bath. Wool flannel is padded with the resulting liquid, as in Example 2, and immediately passed through a boiling 1% aqueous solution of o-phosphoric acid, immersion being for a period of about 35 seconds. On development by exposure to air after issuing from the acid bath, a yellowish-brown dyeing is produced on the fabric which is fast to light and washing.

Example 4 5 parts of a vat dyestuff having the following formula:

OOHS

is vatted by reaction with 5 parts of sodium hydrosulfite and 2.5 parts of caustic soda in 200 parts of water containing 10 parts of a formaldehyde-naphthalene sulfonate and 8 parts of a higher alkylamine-polyethylene oxide condensation product as described in Example 2. The alkaline vat is acidified by addition of 14 parts of 28% acetic acid, the pH of the resulting vat being about 5. Chlorinated Wool is passed continuously through the bath in a padding operation, and directly thereafter passed through 1% aqueous solution of o-phosphoric acid maintained at 200 F., duration of immersion being about one minute. On development after emerging from the bath, the wool is dyed a blue-shade of excellent fastness to light and washing.

The vat dyestuffs suitable for application by the process of this invention are'especiall'y those of the indigoid and bis-arylido-benzoquinone series. Thus, they include, in addition to the dyestuifs of the foregoing examples, bis-indoleindigoes, other bis-thionaphthene-indigoes, bisnaphthindole-indigoes and bis-naphthiopheneindigoes, other indole-naphthalene-indigoes, indole-anthracene-indigoes, indole-acenaphtheneindigoes, indole thionaphthene indigoes, and thionaphthene-acenaphthene-indigoes, which are unsubstituted or which contain one or more nuclear substituents such as chlorine, bromine, methyl, methoxy and ethoxy groups. Similarly, other dianilido-benzoquinones can be employed for dyeing by the present process. In general, vat dyestuffs of the anthraquinone series and condensed polynuclear quinone dyestuffs having a greater number of condensed nuclei than anthraquinone are relatively unsatisfactory for dyeing animal fibre.

In preparing the acidified vat employed in the present process, the vat dyestuff is advantageously vatted in an aqueous bath in the usual manner with an alkali such as caustic soda and a hydrosulfite, e. g. Na hydrosulfite or a derivative thereof, such as sodium formaldehyde sule foxylate or zinc formaldehyde sulfoxylate. Dispersing agents such as the formaldehyde-naphthalene sulfonates of the examples, alkyl aromatic sulfo acids, higher alkyl sulfuric ester salts such as sodium lauryl sulfate or sodium lignin sulfonates can be incorporated in the vat initially, or after conversion of the vat dye to vatted leuco form, but are preferably added before acidification of the vat. The vat is acidified by adding an acid, organic or inorganic, in sufiicient amount to reduce the pH to 3 to 6. Penetration and fixation-promoting materials such as higher alkylamine-ethylene oxide condensation products of the examples or the hydroxyalkyl polyamines mentioned above can be incorporated in the bath at any time before the material to be dyed is treated therewith. The higher alkylamine-ethylene oxide condensation products of the type employed in the examples are preferred since they are especially effective in producing rapid penetration and fixation of the dyestufis on animal fibre in acid medium.

The proportions of the aforesaid components can be varied, suitable proportions being illustrated in the examples. Thus, the vat dye concentration can be between to 6%, the quantity of caustic soda and hydrosulfite being determined by the amount of vat dye employed. A suitable concentration for the aldehydeor alkylnaphthalene sulfonate of the examples is about 1 to 5% of the bath. The higher alkylamineethylene oxide condensation products are advantageously employed in concentrations of 3 .to 6%. In addition to these components, protective colloids such as dextrin, glue, gum tragacanth and the like can also be included in the vat.

The vat is acidified by addition of an acid, preferably an organic acid such as formic or acetic acid, in such amount as to adjust the pH to 3 to 6, and preferably about 5.

The animal fibre material can be wool, chlorinated wool, silk, fur or other animal fibres, and is padded with the resulting acid bath in any manner appropriate for impregnating the material with the dispersion. The padding is preferably carried out progressively and continuously, the time required being quite short, e. g. 5 seconds. After the padding operation, the material is passed directly into the aqueous acid bath of which the pH is within the range of 1 to 3. Suitable acids for this bath are phosphoric, acetic or formic, although other acids can be used, if desired. The temperature of the bath is maintained adjacent the boiling point, particularly from about 200 to 212 F.

Duration of the exposure or immersion of the padded material in the acid bath is generally from to 1 minute. Despite the short period of immersion in the latter bath, the dyestufi is fixed on the fibre, good penetration is obtained, and no substantial loss of dyestufi occurs. Timeconsuming drying operations, steaming or ageing employed in processes heretofore known are thus avoided, and at the same time, the dyestuff is utilized without substantial loss.

Development of the coloration occurs upon exposing the material emerging from the acid bath to air. However, other oxidizing treatments may be employed such as passage through aqueous sulfuric acid-bichromate, persulfate or hydrogen peroxide solutions. Further treatment may include conventional rinsing, soaping and drying operations, and if desired, a treatment with a mild neutralizing agent. The coloration 6 produced shows excellent penetration and is fast to washing and light.

The described process of the invention permits rapid, continuous dyeing of'wool or other animal fibre materials, especially in the form of textile fabrics, with vat dyes in an exceedingly efficient and inexpensive manner, requiring a minimum of apparatus and handling, and affording colorations of excellent fastness properties.

Variations and modifications which will be obvious to those skilled in the art can be made in the procedures hereinbefore described, without departing from the scope or spirit of the invention.

I claim:

1. A process for dyeing animal textile fibre with a vat dye of the class consisting of dyestuffs of the indigoid and bis-arylidobenzoquinone series, which comprises padding the material with an acidic aqueous dispersion having a pH of 3 to 6 of a leuco compound of said vat dyestuif containing a dispersing agent therefor, immersing the padded material in an aqueous acid solution having a pH of 1 to 3 at a temperature of about 200 to 212 R, the duration of the immersion of the material in the latter bath being at least one-half minute, and oxidizing the leuco compound on the fibre.

2. A process for dyeing animal textile fibre with a vat dyestuif, of the class consisting of dyestuffs of the indigoid and bis-arylidobenzoquinone series which comprises padding the material with an acidic aqueous dispersion having a pH of 3 to 6 of a leuco compound of said vat dyestuff including a formaldehyde-naphthalene sulfonate condensation product as the dispersing agent, passing the padded material through an aqueous acid solution having a pH of l to 3 at a temperature of about 200 to 212 F.-, the duration of the immersion of the material in the latter bath being at least one-half minute, and oxidizing the leuco compound on the fibre.

3. A process for dyeing animal textile fibre With a vat dyestuff, of the class consisting of dyestuffs of the indigoid and bis-arylidobenzoquinone series which comprises padding the material with an acidic aqueous dispersion having a pH of 3 to 6 of a leuco compound of said vat dyestuflt containing a dispersing agent therefor, and a fixation accelerator which is the condensation product of a higher alkyl primary monoamine of 12 to 18 carbon atoms with at least 4 molecular equivalents of ethylene oxide, passing the padded material through an aqueous acid solution having a pH of 1 to 3 at a temperature of about 200 to 212 F., the duration of the immersion of the material in the latter bath being at least one-half minute, and oxidizing the leuco compound on the fibre.

4. A process for dyeing animal textile fibre with a vat dyestuff of the class consisting of dyestuffs of the indigoid and bis-arylidobenzoquinone series, which comprises reducing said vat dyestuff in aqueous alkaline medium to leuco form, incorporating a dispersing agent in the resulting vat, acidifying the vat to a pH of 3 to 6, padding said textile fibre with the resulting acidic leuco vat dye dispersion, passing the padded material directly through an aqueous acid solution having a pH of 1 to 3 at a temperature of about 200 to 212 F., the duration of the immersion of the material in said bath being one-half to one minute, and oxidizing the vat dye leuco compound on the fibre.

5. A process for dyeing animal textile fibre witha vat dyestufi oi. the-class consisting, of. dyestuffs of the indigoid and bis-arylidobenzoquinone series, which comprises reducing said vat dyestufi in. aqueous alkaline medium to leuco form, incorporating a dispersing agent in the resulting vat, and further incorporating as a fixation accelerator a condensation product of a higher aliphatic primary monoamine of 12to 18 carbon atoms with at least 4 molecular equivalents of ethylene oxide, acidifying. the vat to a: pH of 3 to 6, paddingv said textile fibre with the resulting, acidic: leuco vat dye dispersion, passing the padded material directly through an aqueous acid solution having a pH of 1 to 3 at a temperature of about 200 to 212 F., the duration of the. immersion of the. material in. said bath being onehalf to one minute, and. oxidizing the vat dye leuco compound on the fibre.

6. In a process for dyeing animal fibre with vat dyes of the class consisting of dyestufis of the indigoid and bis-arylidobenzoquinone series, the improvement which comprises padding the material with. an acid dispersion having a pH of 3 to 6 of the leuco compound of said vat dye, and immersing the material thus padded in an acid bath having apH of 1 to 3 at a temperature of about 200 to 212 F. for a period of at least one-half minute.

7-. In a process. for dyeing animal fibres with vat. dyes of the class consisting of dyestuffs of the indigoid and bis-arylidobenzoquinone series, the improvement which comprises padding the material with an acid dispersion having a pH of 3 to 6 of a. leuco. compound of said vat dye containing as a fixation accelerator a condensation. product of a higher alkyl primary monoamine of 12 to 18 carbon atoms with at least 4. molecular equivalents of ethylene oxide, and passing the material thus padded through an 8 acidbath having apH of 1 to 3 at a temperature of about 200 to 212 F., the duration of immersion of the material in the latter bath being onehalf to one minute.

8. In a process for dyeing animal textile fibre material with a vat dye of the class consisting of dyestuffs of the indigoid and bis-arylidobenzoquinone series, the improvement which comprises preparing an alkaline hydrosulfite vat of said vat dyestufi, incorporating therein a formaldehydenaphthalene sulfonic acid as a dispersing agent, acidifying the resulting bath to a pH of 3 to '5, incorporating in the vat a higher alkyl. primary monoamine of 12 to 18 carbon atoms with at least 4 mole of ethylene oxide, padding the animal fibre material with the resulting bath, immediately thereafter passing the padded material through an acid bath having a pH of 1 to 3 at a temperature of 200 to 212 E, for one-half to one minute, and developing the dyeing by oxidation of the leuco compound absorbed by the fibre.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,900,172 Ellis- Mar. 7, 1933 2,107,526- Dreyfus Feb. 8, 1938 2,450,767 Plotica Oct. 5, 1948 2,552,404 Casty May 8, 1951 FOREIGN PATENTS Number Country Date 355,363 Great Britain. Aug. 27, 1931 OTHER REFERENCES Journal Society Dyers & Colourists for August 1949; pages 381-386. 

1. A PROCESS FOR DYEING ANIMAL TEXTILE FIBRE WITH A VAT DYE OF THE CLASS CONSISTING OF DYESTUFFS OF THE INDIGOID AND BIS-ARYLIDOBENZOQUINONE SERIES, WHICH COMPRISES PADDING THE MATERIAL WITH AN ACIDIC AQUEOUS DISPERION HAVINGA A PH OF 3 TO 6 OF A LEUCO COMPOUND OF SAID VAT DYESTUFF CONTAINING A DISPERSING AGENT THEREFOR, IMMERSING THE PADDED MATERIAL IN AN AQUEOUS ACID SOLUTION HAVING A PH OF 1 TO 3 AT A TEMPERATURE OF ABOUT 200* TO 212* F., THE DURATION OF THE IMMERSION OF THE MATERIAL IN THE LATTER BATH BEING AT LEAST ONE-HALF MINUTE, AND OXIDIZING TH LEUCO COMPOUND ON THE FIBRE. 